[PATCH 3.16 209/233] ipv6: initialize route null entry in addrconf_init()

[Ben Hutchings]

3.16.48-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: WANG Cong <xiyou.wangcong@xxxxxxxxx>

commit 2f460933f58eee3393aba64f0f6d14acb08d1724 upstream.

Andrey reported a crash on init_net.ipv6.ip6_null_entry->rt6i_idev
since it is always NULL.

This is clearly wrong, we have code to initialize it to loopback_dev,
unfortunately the order is still not correct.

loopback_dev is registered very early during boot, we lose a chance
to re-initialize it in notifier. addrconf_init() is called after
ip6_route_init(), which means we have no chance to correct it.

Fix it by moving this initialization explicitly after
ipv6_add_dev(init_net.loopback_dev) in addrconf_init().

Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 include/net/ip6_route.h |  1 +
 net/ipv6/addrconf.c     |  2 ++
 net/ipv6/route.c        | 26 +++++++++++++++-----------
 3 files changed, 18 insertions(+), 11 deletions(-)

--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -69,6 +69,7 @@ struct dst_entry *ip6_route_output(struc
 struct dst_entry *ip6_route_lookup(struct net *net, struct flowi6 *fl6,
 				   int flags);
 
+void ip6_route_init_special_entries(void);
 int ip6_route_init(void);
 void ip6_route_cleanup(void);
 
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -5382,6 +5382,8 @@ int __init addrconf_init(void)
 	if (err)
 		goto errlo;
 
+	ip6_route_init_special_entries();
+
 	for (i = 0; i < IN6_ADDR_HSIZE; i++)
 		INIT_HLIST_HEAD(&inet6_addr_lst[i]);
 
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3141,6 +3141,21 @@ static struct notifier_block ip6_route_d
 	.priority = 0,
 };
 
+void __init ip6_route_init_special_entries(void)
+{
+	/* Registering of the loopback is done before this portion of code,
+	 * the loopback reference in rt6_info will not be taken, do it
+	 * manually for init_net */
+	init_net.ipv6.ip6_null_entry->dst.dev = init_net.loopback_dev;
+	init_net.ipv6.ip6_null_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
+  #ifdef CONFIG_IPV6_MULTIPLE_TABLES
+	init_net.ipv6.ip6_prohibit_entry->dst.dev = init_net.loopback_dev;
+	init_net.ipv6.ip6_prohibit_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
+	init_net.ipv6.ip6_blk_hole_entry->dst.dev = init_net.loopback_dev;
+	init_net.ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
+  #endif
+}
+
 int __init ip6_route_init(void)
 {
 	int ret;
@@ -3166,17 +3181,6 @@ int __init ip6_route_init(void)
 
 	ip6_dst_blackhole_ops.kmem_cachep = ip6_dst_ops_template.kmem_cachep;
 
-	/* Registering of the loopback is done before this portion of code,
-	 * the loopback reference in rt6_info will not be taken, do it
-	 * manually for init_net */
-	init_net.ipv6.ip6_null_entry->dst.dev = init_net.loopback_dev;
-	init_net.ipv6.ip6_null_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
-  #ifdef CONFIG_IPV6_MULTIPLE_TABLES
-	init_net.ipv6.ip6_prohibit_entry->dst.dev = init_net.loopback_dev;
-	init_net.ipv6.ip6_prohibit_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
-	init_net.ipv6.ip6_blk_hole_entry->dst.dev = init_net.loopback_dev;
-	init_net.ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
-  #endif
 	ret = fib6_init();
 	if (ret)
 		goto out_register_subsys;